Advertiser - A company (or person) who is paying to insert an ad and/or promo in episodes within shows.
Baked In - Ads are recorded and inserted into the final cut of an episode, where they live forever. These ads are delivered seamlessly with the audio file of the episode itself.
Campaign - A group of flights sold for the purpose of completing a promotion. These run for a pre-designated length of time and/or pre-designated number of impressions.
Cross Promo - Often an agreement between two or more podcasters/show owners, allowing cross promotion of the others' podcast for increased draw, exposure, and subscribers.
CPM - Cost Per Mile (aka cost per thousand), specifying the cost of the campaign per 1,000 impressions.
Dynamic Ad Insertion (DAI) - Ads are inserted into select episodes dynamically, allowing them to be quickly swapped out with newer, more relevant ads that will allow more advertiser versatility.
Faked In - Ads are recorded and inserted into the final cut of an episode, but the podcaster removes/replaces the ad when they are ready to. The ad [likely] doesn't stay in the episode forever, but it stays until otherwise replaced.
Flight - An individual line-item within a campaign designated for a certain slot, on a certain show (or set of shows), for a certain length of time. Each flight on a show may have a different CPM.
Slots - Spaces within a podcast episode designated for ad insertion. Slots can be found at pre (before the episode begins), mid (at a midway point specified by the podcaster), and post (typically after the episode has completed).
Sponsor - Someone (or some company) that pays for a direct spot in a show, oftentimes personally recorded by the show's host and personally recommending the item/product/services of the sponsor.